No questions found
(a) State why the results in Table 1.2 are qualitative. [1]
(b) Explain why tubes 2, 3 and 4 were included. [2]
(c) State the function of the thin tank of water. [1]
(d) (i) Identify the independent variable and the dependent variable in this investigation.
independent ..............................................................................................................................
dependent ............................................................................................................................... [2]
(ii) Using the apparatus shown in Fig. 1.3, describe a method the student could use to collect the data needed to test their hypothesis.
Your method should be set out in a logical way and be detailed enough to let another person follow it. [7]
(e) Light intensity $(I)$ can be calculated using the formula shown in Fig. 1.4.
$$I = \frac{1}{\text{distance}^2}$$
Use the formula shown in Fig. 1.4 to calculate the light intensity for the investigation shown in Fig. 1.3. [1]
(f) (i) The student concluded that the reaction reached completion at 8 minutes. State why the data in the graph do not support this conclusion. [1]
(ii) Draw a tangent on Fig. 1.5 and use it to calculate the rate of change at 6 minutes.
rate of change at 6 minutes = ..................................... arbitrary units [2]
(iii) On Fig. 1.5, sketch the curve that you would expect for the tube at low light intensity. [1]
(g) (i) Suggest a null hypothesis for the $t$-test used for tubes 1 and 2. [1]
(ii) The $t$-tests were used to compare the means. State one feature of data that allows use of the $t$-test. [1]
(iii) The student calculated that there were 22 degrees of freedom in each of these $t$-tests. An equal number of replicates for each tube was carried out. State the number of replicates of each tube that were carried out. [1]
(iv) The critical value for $t$ at $p<0.05$ in this investigation was 2.07. State what the results in Table 1.4 tell you about the student’s calculated value of $t$ when comparing the effect between weed killers X and Y. [1]
578
591
567
(a) State why the results in Table 1.2 are qualitative. [1]
(b) Explain why tubes 2, 3 and 4 were included. [2]
(c) State the function of the thin tank of water. [1]
(d) (i) Identify the independent variable and the dependent variable in this investigation.
independent ..............................................................................................................................
dependent ............................................................................................................................... [2]
(ii) Using the apparatus shown in Fig. 1.3, describe a method the student could use to collect the data needed to test their hypothesis.
Your method should be set out in a logical way and be detailed enough to let another person follow it. [7]
(e) Light intensity $(I)$ can be calculated using the formula shown in Fig. 1.4.
$$I = \frac{1}{\text{distance}^2}$$
Use the formula shown in Fig. 1.4 to calculate the light intensity for the investigation shown in Fig. 1.3. [1]
(f) (i) The student concluded that the reaction reached completion at 8 minutes. State why the data in the graph do not support this conclusion. [1]
(ii) Draw a tangent on Fig. 1.5 and use it to calculate the rate of change at 6 minutes.
rate of change at 6 minutes = ..................................... arbitrary units [2]
(iii) On Fig. 1.5, sketch the curve that you would expect for the tube at low light intensity. [1]
(g) (i) Suggest a null hypothesis for the $t$-test used for tubes 1 and 2. [1]
(ii) The $t$-tests were used to compare the means. State one feature of data that allows use of the $t$-test. [1]
(iii) The student calculated that there were 22 degrees of freedom in each of these $t$-tests. An equal number of replicates for each tube was carried out. State the number of replicates of each tube that were carried out. [1]
(iv) The critical value for $t$ at $p<0.05$ in this investigation was 2.07. State what the results in Table 1.4 tell you about the student’s calculated value of $t$ when comparing the effect between weed killers X and Y. [1]
544
536
510
(a) Describe a method that the scientists could have used to select the study plots randomly.
..................................................................................................................
..................................................................................................................
..................................................................................................................
.................................................................................................................. [2]
(b) Suggest why counting the dung may not provide an accurate estimate of deer or sheep numbers.
..................................................................................................................
.................................................................................................................. [1]
(c) State two variables that were standardised by the scientists.
1 ..................................................................................................................
..................................................................................................................
2 ..................................................................................................................
.................................................................................................................. [2]
(d) The scientists also counted the number of plant species present within each of the 16 sites.
Fig. 2.2 shows the mean deer dung count for each site and the number of plant species present within each site.
$$\text{[Image Placeholder for Fig. 2.2]}$$
Fig. 2.3 shows the mean deer dung count for the sites containing deer and sheep and for the sites containing deer but no sheep. Range bars are also included.
$$\text{[Image Placeholder for Fig. 2.3]}$$
The report that the scientists read suggested that allowing sheep to graze alongside the deer significantly reduces the need to cull the deer in order to maintain species diversity.
Explain why the results shown in Fig. 2.2 and Fig. 2.3 do not support this suggestion.
..................................................................................................................
..................................................................................................................
..................................................................................................................
.................................................................................................................. [3]
505
503
570
(a) Describe a method that the scientists could have used to select the study plots randomly.
..................................................................................................................
..................................................................................................................
..................................................................................................................
.................................................................................................................. [2]
(b) Suggest why counting the dung may not provide an accurate estimate of deer or sheep numbers.
..................................................................................................................
.................................................................................................................. [1]
(c) State two variables that were standardised by the scientists.
1 ..................................................................................................................
..................................................................................................................
2 ..................................................................................................................
.................................................................................................................. [2]
(d) The scientists also counted the number of plant species present within each of the 16 sites.
Fig. 2.2 shows the mean deer dung count for each site and the number of plant species present within each site.
$$\text{[Image Placeholder for Fig. 2.2]}$$
Fig. 2.3 shows the mean deer dung count for the sites containing deer and sheep and for the sites containing deer but no sheep. Range bars are also included.
$$\text{[Image Placeholder for Fig. 2.3]}$$
The report that the scientists read suggested that allowing sheep to graze alongside the deer significantly reduces the need to cull the deer in order to maintain species diversity.
Explain why the results shown in Fig. 2.2 and Fig. 2.3 do not support this suggestion.
..................................................................................................................
..................................................................................................................
..................................................................................................................
.................................................................................................................. [3]
575
583
590
